In trauma-affected populations untreated sleep disturbances can uphold and exacerbate both sleep-related and non-sleep-related PTSD symptoms. Sleep disturbances may also affect the efficacy of first-line PTSD treatment and constitute a risk factor for poor outcome of psychiatric treatment. It has been argued that effective treatment of sleep disturbances may accelerate recovery in PTSD. There is a lack of randomised clinical trials on this relation in trauma-affected refugees.